Mechanical prosthetic heart valve

ABSTRACT

The invention relates to a mechanical prosthetic heart valve (10) comprising: an annular support (12) having an internal peripheral wall (14) centered about a longitudinal axis (X) and delimiting an internal passage, and at least two mobile leaflets, preferably three mobile leaflets (40), arranged in such a way as to each be able to effect a rotational movement about an axis of rotation perpendicular to said longitudinal axis (X) so that the valve (10) can pass from a closed configuration to an open configuration and vice versa. Each leaflet (40) comprises a leading edge (42) designed to come against a portion of the internal peripheral wall (14) of the annular support (12) when the valve is in a closed configuration, an internal surface (46b) extending from the leading edge (42), and an external surface (46a) opposite the internal surface (46b) and extending from the leading edge (42). The annular support (12) comprises, on the internal peripheral wall (14), at least one lower bearing member (16a, 16b) per leaflet situated between two of said extensions (30) and designed to be in contact against the corresponding leaflet when the valve (10) is in the closed configuration, and two upper bearing members (20a, 20b). The two upper bearing members (20a, 20b) comprise each a distal end (21). Each distal end (21) is designed to come to bear against a bearing zone of the external surface (46a) of the leaflet (40). The center of the bearing zone is set back from the leading edge (42) of the leaflet (40) by a distance greater than a thickness of said leaflet at the center of said bearing zone.

RELATED APPLICATION

The present application claims priority to Swiss Application No. CH00043/20, filed Jan. 14, 2020, the entire contents of which are herebyincorporated by reference.

TECHNICAL FIELD

The present invention relates to a mechanical prosthetic heart valve.

PRIOR ART

A distinction is made between two broad families of prosthetic heartvalves. One of these families covers valve prostheses made of flexibletissue arranged on rigid struts in order to mimic the natural valves,referred to as tissue valves. The other of these families coversmechanical valve prostheses which are devices with no relationship tothe shape of a natural valve and which are manufactured fromwear-resistant and biologically compatible artificial materials.

Because of their anatomical configuration and physiological mode ofoperation, tissue valves offer biological performance aspects similar tothose of a natural heart valve because they conform to the naturalstructure of the flow of blood through the chambers of the heart andthrough the aorta.

This particular feature of tissue valves allows patients to save on theneed for an anticoagulant treatment for the rest of their lives, andthis eliminates the risk of hemorrhagic accidents as a consequence ofthe long-term administration of these medicaments and therefore affordsthese patients a better quality of life. In this way, the patient mayforget that he has a heart valve fitted.

However, these tissue valves have a limited life because theyunavoidably become calcified over time, which means that they need to bereplaced after ten years or so on average. Because of their limitedlife, this type of prosthesis is, in most cases, intended for subjectsover 65 years of age or subjects whose life expectancy is shorter thanthe life of the tissue valves.

Unlike tissue valves, artificial valve devices of mechanical type do notdegrade and have a life that exceeds the span of human life. Since thestart of the 1960s, several generations of mechanical heart valve havebeen successively designed. Mention may be made, for example, of thevalve prostheses consisting of a caged ball (STARR-EDWARDS), then, atthe start of the 1970s, the second-generation prostheses consisting of atiling disk (BJORK-SHILEY) and then, ten years later, the side-openingbi-leaflet third-generation prostheses of the ST-JUDE MEDICAL type.

WO2008152224 discloses a mechanical prosthetic heart valve of the latestgeneration. This heart valve comprises an annular support comprising aninternal peripheral surface centered around a longitudinal axis anddelimiting an internal passage as well as three leaflets arranged insuch a way as to each be able to effect a rotational movement about anaxis of rotation perpendicular to the longitudinal axis so that thevalve can pass from a closed configuration to an open configuration andvice versa. The leaflets between them delimit a main orifice centered onthe longitudinal axis and through which the blood can flow axially whenthe valve is in the open configuration, whereas these leaflets obstructthe internal passage of the annular support so as to be able to preventthe blood from flowing back through the main orifice when the valve isin the closed configuration. Each leaflet comprises a leading edgedesigned to come against a portion of the internal peripheral surface ofthe annular support when the valve is in the closed configuration, acentral part comprising an exterior surface and an interior surface, andtwo lateral wings flanking the central part symmetrically and which areinclined with respect to this central part.

According to the configuration of the valve described in that document,during each cardiac cycle, the leaflets open and close to control theflow of blood. The movement of each leaflet, during the opening and theclosing of the heart valve, is guided, amongst other things, by upperand lower bearing means. The shape and location of the upper bearingmeans on the internal peripheral surface of the annular support are not,however, optimal because these means are in contact with the leafletonly in the vicinity of the leading edge. As a result, the loadingsapplied to the leaflet in this region at the start of opening and at theend of opening are concentrated on areas with a small radius ofcurvature both on the leaflet and on the supports, leading to very highcontact pressures and therefore to significant wear. In addition,according to the configuration of the valve described in that document,the upper bearing means are in contact with the leaflet only during thestart of the opening thereof. When the leaflet has begun its openingmovement, it is then guided between the circular part of the extensionsand a part of the leading edge of the leaflet which comes into contactwith the wall of the annular support. This configuration leads to highforces of reaction between the guide means, something which encouragespremature wear particularly at the level of that zone of the leafletsthat slides along the circular part of the extensions.

It has also been found that, with the impact of leaflet closure, theupper bearing means experience significant loadings to prevent theleaflet from continuing to move beyond the closed position. With a smallcontact area, significant wear is found to occur in this region.

It is an object of the present invention therefore to propose amechanical prosthetic heart valve having improved guidance of theleaflets.

It is another object of the present invention to propose a mechanicalprosthetic heart valve having an improved wear profile.

BRIEF SUMMARY OF THE INVENTION

According to the invention, these objects are achieved by means of amechanical prosthetic heart valve comprising an annular supportcomprising an internal peripheral wall centered about a longitudinalaxis and delimiting an internal passage, and at least two mobileleaflets arranged in such a way as to each be able to effect arotational movement about an axis of rotation perpendicular to thelongitudinal axis so that the valve can pass from a closed configurationto an open configuration and vice versa. The leaflets between themdelimit a main orifice centered on the longitudinal axis and throughwhich blood can flow axially when the valve is in the openconfiguration. The leaflets at least partially obstruct the internalpassage of the annular support so as to be able to prevent the bloodfrom flowing back through the main orifice when the valve is in theclosed configuration. Each leaflet comprises a leading edge designed tocome against a portion of the internal peripheral wall of the annularsupport when the valve is in the closed configuration, an internalsurface extending from the leading edge, and an external surfaceopposite the internal surface and extending from the leading edge. Theannular support comprises two opposite edges and as many as extensionsas the number of leaflets, which extend axially from one of the oppositeedges. The annular support further comprises, on the internal peripheralwall, at least one lower bearing member per leaflet situated between twoof said extensions and designed to be in contact against thecorresponding leaflet when the valve is in the closed configuration, andtwo upper bearing members per leaflet.

The two upper bearing members comprise each a distal end. Each distalend is designed to come to bear against a bearing zone of the externalsurface of the leaflet. The center of the bearing zone is set back fromthe leading edge of the leaflet by a distance greater than the thicknessof said leaflet at the center of the bearing zone.

In an embodiment, the smallest of two principal radii of curvature ofthe surface of the bearing zone is greater than the thickness of theleaflet at said bearing zone.

In an embodiment, each of the two upper bearing members extends inwardlyfrom the internal peripheral wall, and has a proximal end, anintermediate portion, and the distal end having an apex. Theintermediate portion extends from the proximal end inclined in the flowdirection at the predetermined angle to be substantially parallel withthe external surface of said leaflet when the heart valve is in theclosed configuration. The external surface of the leaflet contacts aleading edge of each of the upper bearing members as the leaflet movesfrom the closed configuration to the opened configuration, and pivotsabout the apex of the upper bearing members to rotate the leaflet intothe opened configuration.

In an embodiment, each apex of the two upper bearing members is designedto come to bear against the bearing zone during at least 20% of theopening travel of the leaflet as the valve passes from the fully closedconfiguration to the fully opened configuration.

In an embodiment, each apex of the two upper bearing members is designedto come to bear against said bearing zone during at least 50% of theopening travel of the leaflet as the valve passes from the fully closedconfiguration to the fully opened configuration.

In an embodiment, the leading edge of each of the upper bearing membersis linear.

In an embodiment, the mechanical prosthetic heart valve comprisesexactly two lower bearing members per leaflet.

In an embodiment, in a plane perpendicular to the longitudinal axis ofthe valve, the axis of rotation of each leaflet is situated at adistance from the longitudinal axis that is greater than 75% of theradius of the annular support.

In an embodiment, a profiled recess is created on two opposite sides ofeach extension. The recesses act as guide surfaces for respective twoterminal portions of each leaflet as the valve passes from a closedconfiguration to an open configuration, and vice versa.

In an embodiment, the external surface of each leaflet in the openposition is at a distance from the internal peripherical wall of theannular support at least equal to 5% of the diameter of the annularsupport at a plane of symmetry of the leaflet.

In an embodiment, the material used for the leaflets has a density lessthan 1.5.

Another aspect to the invention relates to a prosthetic heart valvecomprising:

an annular support having an internal peripheral wall and defining aninternal passage centered on a longitudinal axis;

a leaflet having a leading edge, an internal surface extending from theleading edge, an external surface opposite the internal surface andextending from the leading edge, and a trailing edge having a trailingpoint, the leaflet movable between an open configuration that permitsblood to flow through the internal passage in a flow direction along thelongitudinal axis, and a closed configuration that prevents blood fromflowing through the internal passage in the flow direction, said leafletin the closed configuration being inclined at a predetermined angle inthe flow direction from the leading edge to the trailing point, and

an upper bearing member extending inwardly from said internal peripheralwall, the upper bearing member having a proximal end, an intermediateportion, and a distal end having an apex, the intermediate portionextending from the proximal end inclined in the flow direction at thepredetermined angle to be substantially parallel with the externalsurface of said leaflet in closed position.

The external surface of the leaflet contacts a leading edge of the upperbearing member as the leaflet moves from the closed configuration to theopened configuration, and pivots about the apex of the upper bearingmember to rotate the leaflet into the opened configuration.

In an embodiment, the apex is rounded.

In an embodiment, the leading edge of the upper bearing member islinear.

In an embodiment, the prosthetic heart valve further comprises a bearingzone where the apex contacts the external surface of the leaflet. Thecenter of the bearing zone is set back from the leading edge of theleaflet by a predetermined distance.

In an embodiment, the predetermined distance is at least 1 mm.

In an embodiment, the prosthetic heart valve further comprises a gapbetween the leading edge of the upper bearing member and the externalsurface of the leaflet in the closed configuration.

In an embodiment, the prosthetic heart valve comprises at least twoupper bearing members for the leaflet.

In an embodiment, the prosthetic heart valve further comprises a lowerbearing member extending inwardly from the internal peripheral wall atthe leading edge of the internal peripheral wall. The lower bearingmember is adapted to stop movement of the leaflet as the leaflet movesfrom the opened configuration to the closed configuration at a bearingzone positioned at a set distance from the leading edge of the leaflet.

BRIEF DESCRIPTION OF THE FIGURES

Examples of implementations of the invention are indicated in thedescription, which is illustrated by the attached Figures, in which:

FIG. 1 illustrates a perspective view of the mechanical prosthetic heartvalve in an open configuration in which the leaflets between themdelimit a main orifice through which the blood can flow;

FIG. 2 illustrates a perspective view of the mechanical prosthetic heartvalve in a closed configuration in which the leaflets obstruct theinternal passage of the annular support so as to be able to prevent theblood from flowing back through the main orifice;

FIG. 3 illustrates a view of FIG. 1, from above;

FIG. 4 illustrates a view of FIG. 2, from above;

FIG. 5 illustrates a view of FIG. 4 in section on A-A;

FIG. 6 illustrates a view of the annular support, from above;

FIG. 7 illustrates a view of FIG. 6 in section on B-B;

FIG. 8 illustrates a perspective view of the underside of the valve withonly one leaflet;

FIG. 9 illustrates a perspective view or the underside of a leaflet;

FIG. 10 illustrates an enlarged view of a portion of the annular supportof FIG. 6;

FIG. 11 illustrates a view of a leaflet from above, from the side of itsexternal surface;

FIG. 12 illustrates a view of FIG. 11 in section on C-C;

FIG. 13 illustrates a partial perspective view of the mechanicalprosthetic heart valve in the closed configuration with a partialsection in the region of a lower bearing member associated with aleaflet;

FIG. 14 illustrates a view similar to FIG. 13 for a mechanicalprosthetic heart valve according to the prior art;

FIG. 15 illustrates a view similar to FIG. 13 when the mechanicalprosthetic heart valve is in the open configuration;

FIG. 16 illustrates a partial perspective view of the mechanicalprosthetic heart valve in the closed configuration with a partialsection in the region of an upper bearing members associated with aleaflet;

FIG. 17 illustrates a view similar to FIG. 16 when the mechanicalprosthetic heart valve is in the open configuration;

FIG. 18 illustrates a view similar to FIG. 17 for a mechanicalprosthetic heart valve according to the prior art;

FIG. 19 illustrates a partial perspective view of the mechanicalprosthetic heart valve with a leaflet in both a closed configuration andan open configuration;

FIG. 20 illustrates a view similar to FIG. 19 fora mechanical prostheticheart valve according to the prior art;

FIG. 21 illustrates a partial perspective view from underneath themechanical prosthetic heart valve at the level of a flow channel;

FIG. 22 illustrates a partial section through the mechanical prostheticheart valve on a plane perpendicular to the longitudinal axis of theannular support,

FIG. 23 illustrates a view similar to FIG. 22 fora mechanical prostheticheart valve according to the prior art.

FIGS. 24 and 25 are views respectively in section on A-A and on B-B ofFIG. 22 to illustrate the forces exerted on the leaflets upon theopening of the valve, and

FIGS. 26 and 27 are views respectively in section on C-C and on D-D ofFIG. 23 to illustrate the forces exerted on the leaflets upon openingfor a mechanical prosthetic heart valve according to the prior art.

EXAMPLES OF EMBODIMENT OF THE INVENTION

In describing the illustrative, non-limiting embodiments illustrated inthe drawings, specific terminology will be resorted to for the sake ofclarity. However, the disclosure is not intended to be limited to thespecific terms so selected, and it is to be understood that eachspecific term includes all technical equivalents that operate in similarmanner to accomplish a similar purpose. Several embodiments aredescribed for illustrative purposes, it being understood that thedescription and claims are not limited to the illustrated embodimentsand other embodiments not specifically shown in the drawings may also bewithin the scope of this disclosure.

As illustrated notably in FIGS. 1 to 4, a mechanical prosthetic heartvalve 10 comprises a ring-shaped annular support 12 which within itdefines a central internal passage 9 (also see FIG. 6) for the cyclicflow of blood under the action of the contractions of the heart. Theflow passing through the heart valve 10 when the latter is in the openposition is qualified as an antegrade flow and its direction of flow(also referred to herein as the outflow direction) is indicated by thearrow A in FIG. 1. By opposition, the flow flowing in the oppositedirection (also referred to herein as the inflow direction) when theheart valve 10 closes, is qualified as a retrograde flow.

The central internal passage for the flow of blood is delimited by aninternal peripheral wall 14 (FIG. 5) of the annular support 12 whichacts as a support for three mobile leaflets 40. As depicted in FIG. 1,the annular support 12 of the heart valve 10 is centered around alongitudinal axis X and exhibits symmetry of revolution about this axis.It will be noted that the valve may, without this affecting theprinciple of the invention, comprise just two leaflets, in which casethe annular support 12 is of elliptical shape and the leaflets are ovalin shape, or may comprise more than three leaflets.

The annular support 12 also comprises an exterior peripheral wall 22exhibiting a peripheral rim 24 intended to accept a suture ring, notdepicted, for example made of textile, and which allows the surgeon toattach the valve to the heart tissues using sutures in the known way.

In FIGS. 1, 3, the heart valve 10 is depicted in the open configurationin which the leaflets 40 are in what is known as the raised or openposition, the flow of blood passing through the valve in the outflowdirection, whereas in FIGS. 2, 4, the valve is depicted in the closedconfiguration with the leaflets in what is referred to as the lowered orclosed position, preventing blood flow through the heart valve 10 in theinflow direction.

As can be seen in FIG. 5, the annular support 12 comprises an upstreamedge or leading edge 26 connecting the internal peripheral wall 14 tothe exterior peripheral wall 22 and which is positioned on the upstreamside of the antegrade flow. The annular support 12 also comprises adownstream edge or trailing edge 28 which is positioned on thedownstream side of the antegrade flow and which likewise connects theinternal peripheral wall 14 to the exterior peripheral wall 22 of theannular support.

With particular reference to FIGS. 6 and 7, the support 12 alsocomprises three guiding extensions 30 which extend from the trailingedge 28 in the outflow direction, parallel to the direction of thelongitudinal axis X. The guiding extensions 30 thus form projections orcrenellations extending axially with respect to the trailing edge 28 andthe base of which is substantially the same width (dimensionperpendicular to the axis X) as the tip. These guiding extensions 30house profiled recesses 32, in the form of surfaces of revolution, withwhich terminal portions of the mobile leaflets, which will be describedlater, collaborate so that the heart valve 10 can pass from a closedconfiguration to an open configuration and vice versa.

With reference notably to FIG. 11, each leaflet 40 is identical to allthe other leaflets with which the heart valve 10 is equipped. Theleaflet 40 comprises a central part 46 to which there are connected twolateral winglets 48 a, 48 b flanking this central part symmetrically andwhich are inclined with respect thereto as can be seen in particular inFIG. 12. The central part 46 has an external surface 46 a and aninternal surface 46 b, each of which are substantially planar though inone embodiment the internal surface 46 b and/or the external surface 46a can be slightly curved (as shown for the inwardly curved internalsurface 46 b in FIG. 12) to optimize flow characteristics.

The winglets 48 a, 48 b have an external surface 47 a and an internalsurface 47 b, as well as a proximal end portion 43 a, 43 b and a distalend portion 41 a, 41 b, respectively. The external surface 47 a of thedistal end portions 41 a, 41 b can be substantially planar or slightlycurved. The proximal end portion 43 a, 43 b is contiguous with thecentral part 46 and forms a gentle curve inward to the internal passage9 so that the distal end portion 41 a, 41 b forms an angle with respectto the central part 46. In particular, the external surface 47 a of thedistal end portions 41 a, 41 b of the winglets 48 a, 48 b form an anglewith respect to the external surface 46 a of the central part 46, whichin one embodiment can be between 45 and 60 degrees. The leaflet 40 issymmetrical with respect to a plane of symmetry Z. The leaflets 40 arerigid, and can be formed of a rigid material, such as PEEK.

Referring to FIG. 11, the leaflet 40 comprises a trailing point 45, twoterminal portions 49 a, 49 b, a first trailing edge 44 a that extendsbetween the trailing point 45 and the first terminal portion 49 a, asecond trailing edge 44 b that extends between the trailing point 45 andthe second terminal portion 49 b, and a curved leading edge 42 thatextends between the first terminal portion 49 a and the second terminalportion 49 b within the width Wof the leaflet 40. Those elementstogether generally define a triangular shape with an elongated curvedleading edge 42. The external and internal surfaces 46 a, 46 b of thecentral part 46 and winglets 48 a, 48 b is positioned between, and doesnot include, the trailing point 45 and the terminal portions 49 a, 49 b.It is noted that the leading edge 42 (as well as the trailing edges 44)can be rounded, and the external and internal surfaces 46 a, 46 b aredefined to extend from those rounded edges.

When the leaflet is in the open position, as depicted in FIGS. 1 and 3,the leading edge 42 is positioned on the upstream side of the antegradeflow and, in the closed position, mates with the internal wall 14 of theannular support 12 to form a seal that prevents blood flow from passing,as can be seen in FIG. 4. The leading edge 42 of the leaflet extendsfrom a first terminal portion 49 a to a second terminal portion 49 bthese being situated at the distal ends of the respective lateralwinglets 48 a, 48 b. The leading edge 42 is curved to match thecurvature of the internal wall 14.

Furthermore, the leaflet 40 comprises, on the opposite side of theleaflet to the side on which the leading edge 42 is situated, a trailingedge 44 which is positioned on the downstream side of the antegradeflow. The trailing edge 44 comprises two symmetrical portions 44 a, 44 bwhich extend respectively from the lateral winglets 48 a, 48 b as far asa downstream end zone where they meet to form a point 45. The point 45is aligned with the plane of symmetry Z of the leaflet.

The heart valve 10 also comprises several lower (i.e., on the upstreamor leading side) bearing or support members which are different for eachleaflet (each leaflet has its own bearing members 16 a, 16 b) and whichare created on the internal peripheral wall 14 of the annular support12. In particular, with reference notably to FIG. 6, two lower supportor support members 16 a, 16 b (also referring to here as lower bearingor lower bearing members) are arranged between two neighboring guidingextensions 30 to support each leaflet 40 when the heart valve 10 is in aclosed configuration. The lower bearing members 16 a, 16 b arepositioned on the upstream side of the leaflets 40 facing the internalsurface 46 b of the leaflets 40.

According to FIG. 13, the two lower bearing members 16 a, 16 bassociated with each leaflet comprise each a support body 19 with aproximal end 19 a, an intermediate portion, and a distal end forming anapex 18. The intermediate portion has a trailing edge that defines acurved guiding surface 17. The proximal end 19 a is at a proximal sideof the lower bearing members 16 a, 16 b at the juncture between thesupport body 19 and the inner surface 14, and has a curve with a radiiof curvature. The apex 18 extends further in the outflow direction thanthe leading edge 42 and is situated at a distal end of the guidingsurface 17, as may also be seen in FIGS. 8 and 13. The intermediateportion of the guiding surface 17 is located between the proximal end 19a and the apex 18 and is curved away from the apex 18 in the inflowdirection upstream to the antegrade flow.

In addition, the lower bearing members 16 a, 16 b are aligned with thecentral part 46 of the leaflet 40. Thus, in the closed position, a lowerbearing zone 52 is formed where the central part 46 of the internalsurface 46 b of the leaflet 40 comes into contact with the apex 18 ofthe guiding surface 17. The lower bearing zone 52 includes an apexbearing zone (i.e., the part of the apex 18 that touches the leaflet)and the leaflet bearing zone (i.e., the part of the leaflet internalsurface 46 b that touches the apex 18). The apex bearing zone and theleaflet bearing zone cooperate to stop the leaflet 40 as it moves fromthe opened position to the closed position in the antegrade outflowdirection; which in turn defines the closed position for the leaflet 40.However, since the intermediate portion is curved away from the leaflet40, there may be a gap between the intermediate portion of the guidingsurface 17 and the leaflet 40, as illustrated in FIG. 13. That is, inthe embodiment of FIG. 13, the guiding surface 17 extends inward intothe central passage, and upward (i.e., in the outflow flow direction) tothe apex 18.

Moreover, the apex 18 does not touch the leading edge 42, but insteadcontacts a portion of the internal surface 46 b set back from theleading edge 42. Thus, the apex 18 is positioned sufficiently far fromthe leading edge 42 to avoid wear of the leading edge 42 and for theapex 18 to provide structural support, but not too far to interruptflow. It is further noted that in one embodiment the apex 18 of thelower bearing members 16 a, 16 b has a width. Accordingly, the apex andleaflet bearing zones are not a finite point, but can be linear or theapex 18 can be a flat surface (e.g., rectangular or square) to furthersupport the leaflet internal surface 46 b and distribute the force ofthe leaflet 40 contacting the apex 18 and further reduce any hammeringeffect.

The leading edge 42 of each leaflet slides, at least in part, along theguiding surfaces 17 of the two lower bearing members 16 a, 16 b as thevalve passes from an open configuration to a closed configuration. Theleading edge 42 and the internal surface 46 b of the central part 46 ofeach leaflet 40 are in contact with the two lower bearing members 16 a,16 b illustrated notably in FIG. 6 when the valve 10 is in a closedconfiguration as can be seen particularly in FIGS. 8 and 9.

The configuration of the lower bearing members 16 a, 16 b has theadvantage of significantly reducing the wearing of the leaflets byspreading the contact zones, unlike the heart valve according toWO2008152224 in which the contact zones are concentrated at the leadingedge of the leaflet as illustrated in FIG. 14, something which may leadto premature wearing of the leaflets in this zone, thus reducing theoptimal service life of the heart valve. This configuration inparticular ensures that the bearing of the leaflet in the closedconfiguration occurs over its internal surface 46 b. Since the internalsurface 46 b is substantially flat, it has large radii of curvature (seeFIGS. 8 and 9). Thus, the internal surface 46 b need not be completelyflat, but have a sufficiently large radii to increase the contactsurface. The radii of the internal surface 46 a are at least larger thanthe thickness of the leaflet, which is larger than the radii at theleading edge. Only the apex 18 of the guiding surface 17 contacts theinternal surface 46 b of the central part 46 in the closed position.Importantly, the leading edge 42 of the leaflet 40 does not contact theapex 18 and is not utilized to stop movement of the leaflet; whichtherefore avoids wearing of the leading edge 42, avoids any hammeringeffect on the leading edge 42, and ensures a reliable seal between theleading edge 42 and the internal wall 14 in the closed position. Thevery low risk of wearing has the advantage of increasing the diversityof materials that can be employed.

The applicant has found that with respect to the present heart valve 10,the wearing on the leaflet 40 at the zones of contact of the lowerbearing members 16 a, 16 b can be up to 30 microns during acceleratedwearing tests; whereas under the same conditions the wearing on thezones of contact of the support members disclosed in WO2008152224 was inexcess of 100 microns, which can result in leaflet 42 coming free fromthe valve 10.

Thus, it is one aspect of the disclosure that the leading edge 42 of theleaflet not be utilized to stop the motion of the leaflet when theleaflet moves into the closed position. In one embodiment, the leadingedge 42 (which may include part of a rotational curvature at the leadingedge) stays in contact with the guiding surface 17 during rotation ofthe leaflet from the opened position to the closed position, and theinternal surface 46 b only comes into contact with the apex 18 in theclosed position. In that case, the lower bearing zone 52 is positionedaway from the leading edge 42 and also away from any rotationalcurvature of the leading edge 42, so that the bearing zone 52 does notinclude any part of the leaflet that is involved in rotation of theleaflet, to avoid added wear on the rotational elements.

In one embodiment according to FIGS. 9 and 13, the distance d1 betweenthe center of a bearing zone 52 of each apex 18 against the internalsurface 46 b of the central part 46 and the leading edge 42 of eachleaflet is greater than the thickness t1 of the leaflet (for example,the bearing zone 52 cannot be part of the leading edge 42 since theradius of the leading edge 42 is about half of the thickness) at thelevel of the center of the bearing zone 52. This distance d1 is greaterthan 0.5 mm and preferably greater than 1 mm, for a valve 10 having anexternal diameter of 19-29 mm and a leaflet thickness of less than about1 mm (too thick leads to an increased obstruction of the flow in openposition). The radii of curvature of the internal surface of the leafletat the level of the bearing zone 52 are also greater than the thicknesst1 of the leaflet at this point. In the context of the presentdisclosure, the radius of curvature of the internal surface of theleaflet at the bearing zone (wherein the radius of a flat surface isinfinite) is defined as the smallest of the main radii. This also coversa small hole or indent in the leaflet that forms a ball-joint betweenthe leaflet and the apex. Said otherwise, the smallest of two principalradii of curvatures of the surface of the bearing zones 52 is greaterthan the thickness of the leaflet at the bearing zones 52.

The heart valve 10 also comprises support members 34 arrangedsubstantially in the middle and lower part of each guiding extension 30(FIGS. 5 and 7) and which take the form of an element in the shape ofthe bow of a ship pointing upward (i.e., in the antegrade outflowdirection) and profiled in the outflow direction. Each of the profiledelements 34 of the respective guiding extensions 30 comprises lateraledges that are sufficiently widely spaced to act as bearing supports forthe lateral edges of the leaflets 40 when the heart valve 10 is in aclosed configuration.

Furthermore, two so-called upper (i.e., on the outflow side) bearingmembers 20 a, 20 b are arranged, for each leaflet, at the level of thetrailing edge 28 (FIG. 6) of the annular support 12 in a way that isaxially offset along the longitudinal axis X of the annular support 12with respect to the two lower bearing members 16 a, 16 b. The upperbearing members 20 a, 20 b are on the outflow side of the annularsupport (i.e., in the inflow direction), facing the external surface 46a of the leaflets 40. What is more, the two lower bearing members 16 a,16 b and the two upper bearing members 20 a, 20 b for each leaflet mayfor example be offset radially with respect to one another so as toavoid the two upper bearing members 20 a, 20 b being placed in the wakeof the two lower bearing members 16 a, 16 b.

With particular regard to FIGS. 16 and 17, the two upper bearing members20 a, 20 b each can be elongated with a proximal end, distal end, andintermediate portion. The intermediate portion has a leading edge 21′and a trailing edge. The distal end can be a rounded apex 21 designed tocome to bear against the external surface 46 a of the central part 46 ofeach leaflet 40 throughout their pivoting about their respective axis ofrotation as the heart valve 10 passes from the closed configuration tothe open configuration. More particularly, each upper support apex 21 isdesigned to come to bear against an upper bearing zone 54 (FIG. 16) ofthe external surface 46 a of the central part 46 of each leafletthroughout at least 20%, or else 35% or even 50% of the travel of eachleaflet as the heart valve 10 passes from the closed configuration tothe open configuration, something which causes the leaflet to rotateabout its axis of rotation. That contact can be continuous orintermittent. When the leaflet is pushed to open by the flow, thecontact is continuous during the first half of the opening.

The radii of curvature of the upper bearing zone 54 are greater than thethickness of the leaflet at this zone, as for the lower bearing zone 52,or said otherwise the smallest of two principal radii of curvatures ofthe surface of the upper bearing zone 54 is greater than the thicknessof the leaflet at the upper bearing zone 54. As shown in FIG. 17, eachapex 21 is in contact with the external surface 46 a of the central part46 of each leaflet throughout the majority of the opening travel of theleaflet, unlike in the heart valve according to WO2008152224 in whichthe apex of the upper bearing members is in contact with the leafletonly at the very start of the opening phase and in the zone of theleading edge of the leaflet, as illustrated in FIG. 18. The shape of theupper bearing members 20 a, 20 b is therefore significantly different incomparison with the shape of the upper bearing members disclosed inWO2008152224.

In particular, the two upper bearing members 20 a, 20 b of each leafletare in the form of projections that extend inwardly from the internalwall 14 to overlap with the leaflets 40. The two upper bearing members20 a, 20 b are inset from the downstream trailing edge 28 of the support12. In one embodiment, the leading edge 21′ of the upper bearing members20 a, 20 b is substantially linear to match the external surface 46 a ofthe leaflet. In addition, the leading edge 21′, and in one embodimentthe entire bearing member 20 a, 20 b, is inclined with respect to aplane orthogonal to the longitudinal axis X of the annular support 12,to reliably mate with the external surface 46 of the leaflet in theclosed position.

As shown in FIG. 16, the leading edge 21′ of the upper bearing member 20b is substantially parallel to and flush with the external surface 46 aof the leaflet in the closed position. That is, in the closedconfiguration, the external surface 46 a of the leaflet is at apredetermined angle from the leading edge 42 to the trailing edge 44 inthe outflow direction A (see FIGS. 1, 2, 5). In particular, the leadingedge 42 is level and the trailing edge 44 is inclined from the terminalportions 49 to the trailing point 45 in the outflow direction, such thatthe trailing point 45 is further extended in outflow direction than theleading edge 42 and the terminal portions 49, at the predeterminedangle. In addition, the leading edge of the upper bearing member 20 b issubstantially at the same predetermined angle in the outflow directionas the leaflet, so that the bearing leading edge 21′ is substantiallyparallel to and flush with the leaflet external surface 46 a.

The apex 21 at the distal end of the projection is situated beyond thisorthogonal plane when it coincides with the trailing edge 28 of theannular support 12. That is, the apex 21 extends outward from thedownstream trailing edge 28 of the support 12 in the outflow direction.The two upper bearing members 20 a, 20 b each comprise a lower face(i.e., the leading edge) which is parallel to the central part 46 of theleaflets in the closed position.

Referring to FIG. 17, in the opened position, the external surface 46 aof the leaflet is close to the apex 21. At the same time, the curvatureat or adjacent to the leading edge 42 of the leaflet contacts the innersurface of the apex 18 of the lower bearing members 16 a, 16 b (also seeFIG. 15). In the open position, the leaflet is in contact with the lowerbearing members 16 a, 16 b at its leading edge 42 and at the winglet 48a with the extension 30 of the annular support on a surface adjacent tothe recess 32. There is a gap with the apex 21 to avoid sticking. Thosefeatures cooperate to stop further movement of the leaflet 40 from theclosed position to the opened position. The apex 21 does not engage theleading edge 42 of the leaflet 40, but is instead designed to come tobear against a bearing zone 54 (FIG. 16-54 indicates a center of thebearing zone) of the external surface 46 a of the leaflet that is setback from the leading edge 42 of the leaflet by a distance d2 greaterthan the thickness t2 of the leaflet at the center of the bearing zone54; thereby avoiding wear of the leading edge 42 or rotational elements.

The configuration of the upper bearing members 20 a, 20 b offers theadvantage, over WO2008152224, that their point of contact with theleaflet is situated in a low-curvature zone of the leaflet, thuslimiting the risk of wear. Another advantage is that of offering betterguidance of the leaflets when the heart valve 10 passes from a closedconfiguration to an open configuration and of avoiding the leading edgeof the leaflets coming to bear against the internal face of the annularsupport, leading to undesirable reaction forces. According to FIGS. 24and 25, the reaction of the upper bearing members (only the upperbearing member 20 a is visible in FIG. 22) on the leaflet 40 is exactlyopposite to the opening pressure and therefore does not induce anysignificant reaction of the surface of revolution of the recess 32 ofthe extension 30 on the trailing edge 28 of the leaflet 40. Theresultant force on the leaflets 40 is therefore almost zero, therebyconsiderably reducing the wearing of the leaflets.

By contrast, with reference to FIGS. 23, 26 and 27, the reaction at theleading edge of each leaflet, for the heart valve disclosed inWO2008152224, is not parallel to the opening pressure and induces areaction at the trailing edge, something which may lead to prematurewearing of the leaflets. It may also be appreciated from FIGS. 26 and 27that the greater the misalignment between the opening pressure and thereaction at the leading edge, the greater will be the reaction at thetrailing edge. As a result, this particular function of the upperbearing members 20 a becomes all the more important the closer theleaflet is to the closed position.

In order to avoid a risk of jamming with the other members formaintaining an open position (notably the guiding surface 32 and thelower bearing members 16 a, 16 b), there may be a functional clearancebetween the upper bearing members 20 a, 20 b and the external face 46 aof the leaflet in the open position. This arrangement also allows for abroader choice of leaflet materials, for example through the use of amaterial that is a little more sensitive to wear but has a densitycloser to that of blood, offering far less inertia during the phases ofopening and closing. A material such as PEEK has a density of 1.3whereas the pyrolytic carbon commonly employed in mechanical valveprostheses has a density of 1.7.

As depicted in FIGS. 1 and 13, the leading edge 42 of each leaflet 40 isarranged between the two lower bearing members 16 a, 16 b and the twoupper bearing or support members 20 a, 20 b. It will be noted that themembers for guiding the rotation of each leaflet define a virtual axisof rotation depicted in FIG. 22 and situated entirely outside of thecorresponding leaflet, between the latter and the annular support 12.

In operation, at some point the heart valve 10 is in the closedposition, which is best shown in FIGS. 2, 4, 5, 8, 13. The leaflets 40come together at the trailing edges 44, and the leading edge 42 of theleaflet 40 is flush with the inner wall 14, to provide a reliable sealthat prevents blood flow backward. Any blood flow in the inflow(upstream antegrade flow) direction would press the leaflets closed, andfurther movement is prevented at the lower bearing zone 52 by the twolower bearing members 16 a, 16 b, which support each leaflet 40.Specifically, the apex 18 bearing zone supports the internal surface 46b bearing zone to prevent further movement of the leaflet. The lowerbearing members 16 a, 16 b are located between terminal portions 49 a,49 b of the leaflet 40, and the lower bearing zone 52 is set inward apredetermined distance from the leaflet leading edge 42. In addition,the center support member 34 further supports the leaflet winglets 48 a,48 b. Referring to FIG. 13, the leaflet leading edge 42 rests againstthe proximal end of the guiding surface 17. Since the lower bearing zone52 (between the apex 18 and the internal surface 46 b) is away from theleading edge 42, wear on the leading edge 42 is reduced. There is asmall gap between the upper bearing members 20 a, 20 b and the externalsurface 46 a of the leaflet 40, such that the upper bearing members 20a, 20 b are not being utilized in the closed position.

At some point, the leaflets 40 start to move out of the closed positionand toward the opened position. The force of the blood flow moves theleaflet 40 in the outflow direction. That separates the leaflet 40 fromthe apex 18. The leaflet 40 moves in the outflow direction A until, asshown in FIG. 16, the external surface 46 a contacts the bearing leadingedge of the upper bearing members 20 a, 20 b. At this point, turning toFIG. 17, the external surface 46 a contacts the apex 21 of the upperbearing members 20 a, 20 b. That causes the leaflet 40 to rotate aboutthe apex 21 at an upper bearing zone 54, with the winglets 48 a, 48 bguided by the recesses 32 of the guide extension 30. The upper bearingzone 54 is set back from the leading edge 42 by a predetermineddistance. The trailing edges 44 of the leaflet 40 rotate to extend inthe outflow direction. And the leading edge 42 rotates toward the innersurface of the lower support apex 18. Because the leaflet 40 isseparated from the guiding surface 17, the leading edge 42 does notcontact the guiding surface 17 during rotation, which reduces wear onthe leading edge 42. The leaflets 40 are stopped when the winglets 48contact the edge of the recesses 32, and the leaflet 40 contacts theinner surface of the lower support apex 18.

When the blood flows in the inflow direction, the blood forces theleaflets from the opened position to the closed position. The leadingedge 42 of the leaflet is guided by the guiding surface 17 of the lowerbearing members 16 a, 16 b. The motion of the leaflet stops when theinternal surface 46 b of the leaflet contacts the apex 18.

It is noted that in the embodiments shown, there are three leaflets 40and three guide extensions 30. In addition, each leaflet 40 has twolower bearing members 16 a, 16 b and two upper bearing members 20 a, 20b. Having two lower and upper bearing members 16 a, 16 b, 20 a, 20 bdistributes wear and pressure more evenly across the leaflet and reduceswear on the leaflet 40. However, any suitable number of elements can beprovided, including more or fewer leaflets 40 and guide extensions 30.And each leaflet can have one or more lower bearing members and/or upperbearing members.

The applicant has found that according to the valve configurationdescribed in WO2008152224, the leading edges of the two winglets of eachleaflet slide against the internal peripheral surface of the annularsupport as the leaflets rotate at the start of systole. Now, it has beenfound that constant contact between the leading edges and the internalperipheral wall of the annular support according to FIG. 20, whichdepicts a partial section through the mechanical prosthetic heart valvedisclosed in WO2008152224 on a plane perpendicular to the longitudinalaxis of the annular support, may create a flow recirculation in theobstructed zone behind the leaflets that encourages platelet aggregationand thrombus formation.

According to FIGS. 11, 12 and 22, the curvature of the proximal portion43 b of the lateral winglets 48 a, 48 b (FIG. 12) of each leaflet 40 hasbeen determined so that the leading edge 42 and the external face ofeach leaflet 40 are distant from the internal peripheral wall by atleast 0.2 mm, preferably by at least 0.3 mm, or else 0.4 mm or even 0.5mm, over at least 75% of the total width W of each leaflet andpreferably over at least 80%, or else 90% when the heart valve 10 is inthe open configuration. The curvature of the lateral winglets 48 a, 48 bof each leaflet 40 has also been determined to encourage the opening ofthe flow channels 50 (FIGS. 21 and 22) between the internal peripheralwall 14 of the annular support 12 and the external surface 47 a of thewinglets 48 a, 48 b of the leaflets 40.

In particular, when the leaflets are in the open position according toFIG. 1, each leaflet is in contact with the internal peripheral wall 14of the annular support 12 only through the two end portions 49 a, 49 bof the leaflet as can be seen on FIG. 22. Advantageously, the contactzone of the leaflet in the open position is less than 15% of the totalwidth W of the leaflet 40 extending between the extremities of the twoterminal portions 49 a, 49 b (FIGS. 11 and 12), i.e. less than 7.5% ateach terminal portion 49 a, 49 b. In a preferred embodiment, thiscontact zone of the leaflet is less than 10% of the width W of theleaflet 40, i.e. less than 5% at each terminal portion 49 a, 49 b of theleaflet, preferably less than 7.5% of the width W of the leaflet 40,i.e. less than 3.75% at each terminal portion 49 a, 49 b of the leaflet,and even more preferably less than 5% of the width W of the leaflet 40,i.e. less than 2.5% at each terminal portion 49 a, 49 b of the leafletas illustrated in FIG. 22. In the context of the present invention, theextensions 30 of the annular support 12 are an integral part of theinternal peripheral wall 14 of the support and, therefore, the leafletcontact zone at the extensions 30 must be included in the abovepercentages.

Furthermore, as shown in FIGS. 3, 11 and 12, the external surface 46 aof each leaflet 40 in the open position is at a distance L from theinternal peripherical wall 14 of the annular support 12 at least equalto 5% of the diameter of the annular support at a plane of symmetry Z ofthe leaflet.

As can be seen in FIG. 22, the axis of rotation of each leaflet 40 isalso situated in a plane parallel to the central part 46 of the leaflet.This plane intersects the two upper bearing members 20 a, 20 b arrangedon the internal peripheral wall 14 of the annular support 12. The axisof rotation of each leaflet is also situated at a distance from thelongitudinal axis X of the annular support 12 of the heart valve 10 (ina plane perpendicular to this axis), which distance is greater than 75%of the radius of the annular support 12.

As best shown in FIG. 3, the leaflets 40 are configured in the openedposition, to form a substantially triangular shape with rounded cornerswhen arranged in the support 12. The terminal portions 49 of theleaflets 40 engage with the extensions 30, and the planar central part46 of the leaflets 40 extend substantially linearly between theextensions 30. Accordingly, the planar central part 46 extends inwardlyfrom the terminal portions 49 of the winglets 48 to the center of thecentral part 46, which is at the furthest distance to the inner wall 14of the support 12. In addition, as best shown in FIG. 22, in the openedposition, the external surface 47 of the distal end portion 41 extendssubstantially parallel to the inner wall 14 and contacts the recess 32.

In addition, the curved proximal end portion 43 is configured to beginat the end of the recess, so that the winglet 48 immediately turnssharply away from the inner wall 14 of the support 12, forming the gap50 between the external surface 47 of the proximal end portion 43 andthe inner wall 14 of the support 12 that forms a channel through whichblood can flow. Accordingly, the distal end portion 41 extends axiallyoutward from the extension 30, then curves inward at the curved proximalportion 43. The central part 46 extends linearly between the extensionsand continues to move away from the inner wall 14 forming a larger gapbetween the external surface 46 a of the central part 46 and inner wall14. The channel formed by the gap 50 allows blood to more easily flow inthe outflow direction. In addition, the straight central part 46 alsominimizes interference with blood flow. Thus, the configuration of theleaflets 40 as arranged with the proximal portions 49 positioned at theextensions 30 and curving immediately inwardly in a linear fashion tothe next neighboring extension 30, provides a widened gap 50 or channelbetween the leaflets 40 and the inner wall 14. In one embodiment, thedistal end portion 41 can also be curved inwardly to further widen thegap 50 just to the sides of the extensions 30.

As further illustrated in FIG. 3, the center of the central part 46 isthe largest distance between the leaflet 40 and the inner wall 14. Thelower support or bearing members 16 a, 16 a are positioned at the innerwall 14 at the outermost part of the central part 46, just adjacent tothe curved proximal end portion 43 of the winglet 48, to providesufficient support as the leaflet 40 enters the closed position. Theupper bearing members 20 a, 20 b can be positioned closer together atthe central part 46.

The curvature of the proximal portion 43 of the lateral winglets 48 a,48 b of each leaflet 40 and the shape and positioning of the two lowerbearing members 16 a, 16 b makes it possible to form two flow channels50 at the level of the terminal portions 49 a, 49 b of each leaflet 40between each of the two lower bearing members 16 a, 16 b and one of theguiding extensions 30 of the annular support 12 when the heart valve 10passes from a closed configuration to an open configuration. Indeed, thegap 50 between the leading edge 42 of the leaflet 40 and the trailingedge 28 of the annular support 12 are defined by the specific curvatureof the leaflets, the profile of the trailing edge 28, and the shift ofthe axis of rotation that put the leaflet a bit more downstream withrespect to the internal peripheral wall 14 in the open position. Thedimensions of each flow channel 50, which is illustrated in particularin FIGS. 19, 21 and 22, increase as the leaflets 40 progressively pivotabout their respective axis of rotation until such point as the heartvalve 10 is in the open configuration. These flow channels have theadvantage of minimizing the potential platelet aggregation zones.

By contrast, the heart valve according to WO2008152224 has no flowchannels at the level of the terminal portions of each leaflet betweeneach of the two lower bearing members and one of the guiding extensionsof the annular support when the heart valve passes from a closedconfiguration to an open configuration, as can be seen in FIG. 23. Thisis mainly due to the contact zone of the leaflet, which is about 20% ofthe total width of the leaflet, i.e. 10% at each terminal portion of theleaflet as shown in FIG. 23. The absence of discharge channels in thesecritical zones may lead to an aggregation of platelets which couldinduce a thrombosis.

In order to manufacture the rigid-leaflets valve according to theinvention, there are various materials that can be used. For the annularsupport, a biocompatible metal such as titanium or stellite for exampleis selected. It may also be possible to use solid carbon, or else acarbon coating on graphite.

The leaflets themselves are also rigid, and may be made from abiocompatible material, for example monolithic carbon, or from graphitewith a coating of pyrolytic carbon. The leaflets may also be made from abiocompatible synthetic polymer which also has wear resistanceproperties comparable to those of pyrolytic carbon. Thus, a materialsuch as “PEEK” (which stands for polyetheretherketone) has a low densityof the order of 1.3 and is particularly suitable for the manufacture ofthe leaflets. This material may be reinforced with carbon in order toincrease the wear resistance of the leaflets.

It will be noted that the valve according to the invention can be madeof titanium in the case of the annular support 12 and of PEEK for theleaflets, something which affords a pairing of materials that isperfectly suited to the rubbing and wearing encountered in this type ofvalve. Furthermore, PEEK can also be used as a material formanufacturing the leaflets and pyrolytic carbon for the support, or evenpyrolytic carbon for the leaflets and the support.

It is further noted that the drawings may illustrate and the descriptionand claims may use several geometric or relational terms and directionalor positioning terms, such as profiled, square, rectangular, triangular,linear, curved, curvature, rounded, parallel, perpendicular, orthogonal,transverse, axially, circular, flat, leading, trailing, forward, upper,lower, up, down, inner, outer, internal, external, side, distal, andproximal. Those terms are merely for convenience to facilitate thedescription based on the embodiments shown in the figures, and are notintended to limit the invention. Thus, it should be recognized that theinvention can be described in other ways without those geometric,relational, directional or positioning terms. In addition, the geometricor relational terms may not be exact. For instance, walls or surfacesmay not be exactly flat, perpendicular or parallel to one another butstill be considered to be substantially perpendicular or parallelbecause of, for example, roughness of surfaces, tolerances allowed inmanufacturing, etc. And, other suitable geometries and relationships canbe provided without departing from the scope of the appended claims.

It will be apparent to those skilled in the art having the benefit ofthe teachings presented in the foregoing descriptions and the associateddrawings that modifications, combinations, sub-combinations, andvariations can be made without departing from the spirit or scope ofthis disclosure. Likewise, the various examples described may be usedindividually or in combination with other examples. Those skilled in theart will appreciate various combinations of examples not specificallydescribed or illustrated herein that are still within the scope of thisdisclosure. In this respect, it is to be understood that the disclosureis not limited to the specific examples set forth and the examples ofthe disclosure are intended to be illustrative, not limiting.

LIST OF REFERENCES

-   Mechanical prosthetic heart valve 10-   Annular support 12-   Internal peripheral wall 14-   Lower bearing members 16 a, 16 b-   Support body 19-   Proximal end 19 a-   Guiding surface 17-   Apex 18-   Upper bearing members 20 a, 20 b-   Apex 21-   Leading edge 21′-   Exterior peripheral wall 22-   Peripheral rib 24-   Leading edge 26-   Trailing edge 28-   Guiding extensions 30-   Profiled recess 32-   Guiding arc-   Bearing members 34-   Mobile leaflets 40-   Leading edge 42-   Trailing edge 44-   Symmetrical portions 44 a, 44 b-   Tip 45-   Central part 46-   External surface 46 a-   Internal surface 46 b-   Lateral winglets 48 a, 48 b-   Distal end portions 41 a, 41 b-   Proximal end portions 43 a, 43 b-   External surface 47 a-   Internal surface 47 b-   Terminal portions 49 a, 49 b-   Flow channel 50-   Lower bearing zones 52-   Upper bearing zones 54

1. A mechanical prosthetic heart valve comprising: an annular supportcomprising an internal peripheral wall centered about a longitudinalaxis and delimiting an internal passage, at least two mobile leafletsarranged in such a way as to each be able to effect a rotationalmovement about an axis of rotation perpendicular to the longitudinalaxis so that the valve can pass from a closed configuration to an openconfiguration and vice versa, the leaflets between them delimiting amain orifice centered on the longitudinal axis and through which bloodcan flow axially when the valve is in the open configuration, theleaflets at least partially obstructing the internal passage of theannular support so as to be able to prevent the blood from flowing backthrough the main orifice when the valve is in the closed configuration,each leaflet comprising a leading edge designed to come against aportion of the internal peripheral wall of the annular support when thevalve is in the closed configuration, an internal surface extending fromthe leading edge, and an external surface opposite the internal surfaceand extending from the leading edge, the annular support comprising twoopposite edges and as many as extensions as the number of leaflets,which extend axially from one of the opposite edges, the annular supportfurther comprising, on the internal peripheral wall, at least one lowerbearing member per leaflet situated between two of said extensions anddesigned to be in contact against the corresponding leaflet when thevalve is in the closed configuration, and two upper bearing members perleaflet, wherein said two upper bearing members comprise each a distalend, each distal end being designed to come to bear against a bearingzone of the external surface of the leaflet, wherein the center of saidbearing zone is set back from the leading edge of the leaflet by adistance greater than the thickness of said leaflet at the center ofsaid bearing zone.
 2. The mechanical prosthetic heart valve of claim 1,wherein the smallest of two principal radii of curvature of the surfaceof the bearing zone is greater than the thickness of the leaflet at saidbearing zone.
 3. The mechanical prosthetic heart valve of claim 1,wherein each of said two upper bearing members extends inwardly fromsaid internal peripheral wall, and has a proximal end, an intermediateportion, and the distal end having an apex, each intermediate portionextending from the proximal end inclined in the flow direction at thepredetermined angle to be substantially parallel with the externalsurface of said leaflet when the heart valve is in the closedconfiguration, wherein the external surface of said leaflet contacts aleading edge of each of said upper bearing members as the leaflet movesfrom the closed configuration to the opened configuration, and pivotsabout the apex of said upper bearing members to rotate said leaflet intothe opened configuration.
 4. The mechanical prosthetic heart valve ofclaim 3, wherein each apex of the two upper bearing members is designedto come to bear against said bearing zone during at least 20% of theopening travel of the leaflet as the valve passes from the fully closedconfiguration to the fully opened configuration.
 5. The mechanicalprosthetic heart valve of claim 3, wherein each apex of the two upperbearing members is designed to come to bear against said bearing zoneduring at least 50% of the opening travel of the leaflet as the valvepasses from the fully closed configuration to the fully openedconfiguration.
 6. The mechanical prosthetic heart valve of claim 3,wherein the leading edge of each of said upper bearing members islinear.
 7. The mechanical prosthetic heart valve of claim 1, whereinsaid valve comprises exactly two lower bearing members per leaflet. 8.The mechanical prosthetic heart valve of claim 1, wherein, in a planeperpendicular to the longitudinal axis of the valve, the axis ofrotation of each leaflet is situated at a distance from the longitudinalaxis that is greater than 75% of the radius of the annular support. 9.The mechanical prosthetic heart valve of claim 1, wherein a profiledrecess is created on two opposite sides of each extension, the recessesacting as guide surfaces for respective two terminal portions of eachleaflet as the valve passes from a closed configuration to an openconfiguration, and vice versa.
 10. The mechanical prosthetic heart valveof claim 1, wherein the external surface of each leaflet in the openposition is at a distance from the internal peripherical wall of theannular support at least equal to 5% of the diameter of said annularsupport at a plane of symmetry of the leaflet.
 11. The mechanicalprosthetic heart valve of claim 1, wherein the material used for theleaflets has a density less than 1.5.
 12. A prosthetic heart valvecomprising: an annular support having an internal peripheral wall anddefining an internal passage centered on a longitudinal axis; a leaflethaving a leading edge, an internal surface extending from the leadingedge, an external surface opposite the internal surface and extendingfrom the leading edge, and a trailing edge having a trailing point, saidleaflet movable between an open configuration that permits blood to flowthrough the internal passage in a flow direction along the longitudinalaxis, and a closed configuration that prevents blood from flowingthrough the internal passage in the flow direction, said leaflet in theclosed configuration being inclined at a predetermined angle in the flowdirection from the leading edge to the trailing point; and an upperbearing member extending inwardly from said internal peripheral wall,said upper bearing member having a proximal end, an intermediateportion, and a distal end having an apex, the intermediate portionextending from the proximal end inclined in the flow direction at thepredetermined angle to be substantially parallel with the externalsurface of said leaflet in closed position; wherein the external surfaceof said leaflet contacts a leading edge of said upper bearing member asthe leaflet moves from the closed configuration to the openedconfiguration, and pivots about the apex of said upper bearing member torotate said leaflet into the opened configuration.
 13. The prostheticheart valve of claim 12, wherein said apex is rounded.
 14. Theprosthetic heart valve of claim 12, wherein the leading edge of saidupper bearing member is linear.
 15. The prosthetic heart valve of claim12, further comprising a bearing zone where the apex contacts theexternal surface of said leaflet, wherein the center of said bearingzone is set back from the leading edge of said leaflet by apredetermined distance.
 16. The prosthetic heart valve of claim 15,wherein the predetermined distance is at least 1 mm.
 17. The prostheticheart valve of claim 12, further comprising a gap between the leadingedge of said upper bearing member and the external surface of saidleaflet in the closed configuration.
 18. The prosthetic heart valve ofclaim 12, comprising at least two upper bearing members for saidleaflet.
 19. The prosthetic heart valve of claim 18, further comprisinga lower bearing member extending inwardly from the internal peripheralwall at the leading edge of said internal peripheral wall, said lowerbearing member stopping movement of the leaflet as the leaflet movesfrom the opened configuration to the closed configuration at a bearingzone positioned at a set distance from the leading edge of the leaflet.